1. Field of the Invention
The present invention relates to an improved orthotic particularly arranged and adapted to be made by a relatively convenient and rapid process or method, and also to the method of making the orthotic.
2. Background Art
An orthotic insert can be either soft or hard. A hard insert is a substantially rigid member, desirably having a relatively thin vertical thickness dimension and extending from the calcaneus area of the foot (the heel portion) to at least the metatarsal head area of the foot (i.e. that area at the "ball" of the foot). In general, the purpose of a rigid orthotic (sometimes called a functional orthotic) is to first position, and then to control the movements of, the midtarsal and subtalar joints during the gait cycle which the body goes through in walking and running, and also possibly for other movements.
A common method of making an orthotic insert is first to prepare a negative mold of a person's foot, such as a plaster of paris mold. One desirable way of accomplishing this is described in U.S. Pat. No. 3,995,002, entitled "Orthocasting System", the inventor being the same as the applicant herein. In that method, a moldable material is placed against the bottom of the person's foot, and a flexible plastic bag is placed around the moldable material and the person's foot, so as to extend upwardly around the person's ankle. Further, a suction hose is p1aced within the bag so that the inlet to the hose is positioned on the upper part of a person's foot. A vacuum is applied to cause atmospheric pressure to press against the bag and also press the moldable material upwardly against the plantar surface (i.e. bottom surface) of the person's foot, and also a short distance upwardly around the side of the person's foot. The operator properly positions the person's foot so that the mold is properly formed in the desired configuration. Generally, this will be accomplished by the operator placing the person's foot in the neutral position and manipulating the forward part of the foot so that the midtarsal joint is in the locked or nearly locked position. This may vary somewhat, depending upon individual considerations in making the orthotic.
After the moldable material has hardened to make the mold, the plastic bag and the mold are removed. Then a positive cast is made from the mold (this generally being a plaster of paris cast, the contours of which correspond to the person's foot). From this positive cast, the orthotic can be made.
It is also known in the prior art to make an orthotic insert by preheating a moldable material, such as a cork-like material, and placing this in a relatively rigid base member having the general contour of a person's foot. The base member and the moldable cork material (which is heated to make it more yielding, and thus moldable) is placed against the person's foot, and the plastic bag is then placed around the base member, the moldable cork material, and the person's foot. A vacuum is applied as described above, and the moldable cork material cools to make the orthotic insert. The base member is removed from the orthotic insert, and this base member can be used again in subsequent molding of an orthotic.
As a modification of the process noted above, instead of using a reusable base member, which does not become part of the orthotic, a relatively rigid cap can be utilized, with this cap becoming part of the finished orthotic. In this particular method, the moldable cork-like material is placed within the cap, along with an upper yielding blank, and in the preferred embodiment an intermediate flexible member. The cork-like material is heated so as to be yielding and thus moldable, and the cap can also be heated, primarily to keep the cork-like material at an adequately high temperature during the forming process. Then the vacuum bag is applied and the vacuum imposed, as described above. The components are then permitted to cool, with the cap, the cork material, the flexible blank and the flexible insert forming the finished orthotic. Such a procedure is described in pending U.S. patent application Ser. No. 766,049, now U.S. Pat. No. 4,597,196, entitled "Improved Orthotic Insert and Method of Making the Same", the inventor being the same as the applicant herein.
To turn our attention now to other aspects relevant to the background of the present invention, there will now be a discussion of the following: (a) the main components or parts of the human leg and foot and how these function relative to one another; (b) the gait cycle which a person goes through in a normal walking motion; and, (c) the intended function of a rigid orthotic in optimizing the coordinated operation of the person's foot and leg throughout the gait cycle.
For convenience, these various topics will be discussed under appropriate subheadings.